Macrophage-like cell line (HS-P) from a rat histiocytic sarcoma

With future exploration of macrophage properties in mind, we established a novel cell line (HS-P) from a transplantable histiocytic sarcoma, derived o riginally from a tumour in an aged F344 rat. HS-P was subjected to 70 seria l passages, in which the mean doubling time was 15.7 h. The cells, which we re round, oval or polygonal in shape, were arranged in a compact sheet. The y reacted to varying degrees for lysosomal enzymes (acid phosphatase and no n-specific esterase) and with the following antibodies: ED1/ED2 (rat macoph age/histiocyte-specific), OX6 (rat MHC class II-specific), lysozyme antibod y and alpha1-antichymotrypsin antibody. Electron microscopically, HS-P cell s showed lysosomes and prominent cell projections. These findings indicated that the cultured cells were macrophage-like. Syngeneic rats inoculated su bcutaneously or intraperitoneally with HS-P cells invariably developed sarc omatous tumours consisting of monomorphic mononuclear cells, which exhibite d cytochemical properties similar to those of cultured HS-P cells. Bioassay and reverse transcription-polymerase chain reaction methods revealed that tumour necrosis factor-alpha increased on addition of lipopolysaccharide (L PS), indicating that HS-P cells remained LPS-responsive. HS-P cells may pro ve to be a useful tool for in-vitro studies of macrophage function. (C) 200 1 Harcourt Publishers Ltd.